bpo-32677: Add .isascii() to str, bytes and bytearray (GH-5342)

diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 0733011..4b90cc3 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -11612,6 +11612,25 @@
 }
 
 /*[clinic input]
+str.isascii as unicode_isascii
+
+Return True if all characters in the string are ASCII, False otherwise.
+
+ASCII characters have code points in the range U+0000-U+007F.
+Empty string is ASCII too.
+[clinic start generated code]*/
+
+static PyObject *
+unicode_isascii_impl(PyObject *self)
+/*[clinic end generated code: output=c5910d64b5a8003f input=5a43cbc6399621d5]*/
+{
+    if (PyUnicode_READY(self) == -1) {
+        return NULL;
+    }
+    return PyBool_FromLong(PyUnicode_IS_ASCII(self));
+}
+
+/*[clinic input]
 str.islower as unicode_islower
 
 Return True if the string is a lowercase string, False otherwise.
@@ -13801,6 +13820,7 @@
     UNICODE_UPPER_METHODDEF
     {"startswith", (PyCFunction) unicode_startswith, METH_VARARGS, startswith__doc__},
     {"endswith", (PyCFunction) unicode_endswith, METH_VARARGS, endswith__doc__},
+    UNICODE_ISASCII_METHODDEF
     UNICODE_ISLOWER_METHODDEF
     UNICODE_ISUPPER_METHODDEF
     UNICODE_ISTITLE_METHODDEF